Ink jet recording apparatus utilizing printhead cartridges with asymmetrical contacts

ABSTRACT

A printhead cartridge mounts within a carriage of a printer. The carriage moves along a first direction within the printer. The printhead cartridge includes an inkwell for storing ink, which has a front surface and a bottom surface, a printhead mounted on the bottom surface, and a plurality of contacts for receiving signals from the printer and to provide the signals to the printhead. A centerline of the front surface, running perpendicular to the first direction, evenly defines first and second sides of the front surface. The contacts are disposed on the front surface, and a distribution of the contacts on the first side exceeds a corresponding distribution of the contacts on the second side.

CROSS REFERENCE TO RELATED APPLICATIONS

The following is a division of U.S. application Ser. No. 09/682,300,filed Aug. 16, 2001, now U.S. Pat. No. 6,533,396 which is includedherein by reference.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to an ink jet recording apparatus (IJRA).In particular, the present invention discloses an IRJA that utilizesprinthead cartridges with asymmetrical contacts to enable a sizereduction in a corresponding flexible circuit board (FCB) within theIRJA.

2. Description of the Prior Art

Please refer to FIG. 1. FIG. 1 is a perspective view of a prior artprinthead cartridge 10. The prior art printhead cartridge 10 comprisesan inkwell 12 and a tape automated bonding (TAB) structure 14. The TAB14 is mounted on the inkwell 12, wrapping around from a front surface 15to a bottom surface 19. The TAB 14 comprises a plurality of contacts 16,each with a corresponding trace 17 that electrically connects to aprinthead 18. The printhead 18 is mounted on the TAB 14, and is disposedon the bottom surface 19 of the inkwell 12. The printhead cartridge 10exhibits great symmetry along a cross-section A—A. If the printheadcartridge 10 were to be split down the middle along the line A—A, eachhalf of the printhead cartridge 10 would have approximately the samenumber of contacts 16 (depending upon the parity of the number ofcontacts 16), and half of the printhead 18. The inkwell 12 is used tohold ink (not shown), and to provide this ink to the printhead 18. Theprinthead 18 performs a printing operation by jetting ink according tosignals received from the contacts 16.

Please refer to FIG. 2 with reference to FIG. 1. FIG. 2 is a perspectiveview of a prior art printer 20. The printhead cartridge 10 is adaptedfor use in the printer 20. The printer 20 has a carriage 22 that holdstwo of the printhead cartridges 10, carrying the printhead cartridges 10back and forth along a print track 24. The two printhead cartridges 10are held as closely together as possible within the carriage 22. Witheach pass along the track 24, the printhead cartridges 10 form a printswath on a sheet of paper 21. Generally speaking, one of the printheadcartridges 10 performs a black-and-white printing operation, whereas theother printhead cartridge 10 performs a color printing operation usingcyan, magenta and yellow inks. Together, the two printhead cartridges 10are able to perform a full-color printing process upon the sheet ofpaper 21.

Please refer to FIG. 3 with reference to FIGS. 1 and 2. FIG. 3 is aschematic diagram of a flexible circuit board (FCB) 30 within theprinter 20. The FCB 30 is disposed within the carriage 22 and is used toestablish electrical communications with the printhead cartridges 10.The FCB 30 has a plurality of dimples 36, each of which establishes anelectrical connection with one of the corresponding contacts 16 of theprinthead cartridges 10. In this manner, the printer 20 is able tocontrol the printhead 18 of each printhead cartridge 10.

The cost associated with the FCB 30 is related to the overall surfacearea of the FCB 30. By reducing the size of the FCB 30, it should bepossible to reduce the total cost of the printer 10.

SUMMARY OF INVENTION

It is therefore a primary objective of this invention to provide an inkjet recording apparatus (IRJA) that utilizes printhead cartridges havingan asymmetric distribution of contacts to reduce a size of acorresponding contact surface within the IRJA.

Briefly summarized, the preferred embodiment of the present inventiondiscloses a printhead cartridge that mounts within a carriage of aprinter. The carriage moves along a first direction within the printer.The printhead cartridge includes an inkwell for storing ink, which has afront surface and a bottom surface, a printhead mounted on the bottomsurface, and a plurality of contacts for receiving signals from theprinter and to provide the signals to the printhead. A centerline of thefront surface, running perpendicular to the first direction, evenlydefines first and second sides of the front surface. The contacts aredisposed on the front surface, and a distribution of the contacts on thefirst side exceeds a corresponding distribution of the contacts on thesecond side.

It is an advantage of the present invention that by providing anasymmetric distribution of the contacts of the front surface of aprinthead cartridge, two such mirrored cartridges will form a combineddensity of contacts that is higher towards their combined centerposition. The traces on a contact surface within the carriage of theprinter can be made to run between two columns of dimples. The size ofthe corresponding contact surface can be reduced as a result of this,which leads to a total lower cost of the printer.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment, which isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a prior art printhead cartridge.

FIG. 2 is a perspective view of a prior art printer.

FIG. 3 is a schematic diagram of a flexible circuit board (FCB) withinthe printer of FIG. 2.

FIG. 4 is a perspective view of a preferred embodiment of a printheadcartridge according to the present invention.

FIG. 5 is a perspective view of a printer according to the presentinvention.

FIG. 6 is a perspective view of printhead cartridges according to thepresent invention, which are to be used in the printer of FIG. 5.

FIG. 7 is a schematic diagram of a flexible circuit board (FCB) disposedwithin a carriage of the printer of FIG. 5.

FIG. 8 is a perspective view of a second embodiment printhead cartridgeaccording to the present invention.

FIG. 9 is a perspective view of a third embodiment printhead cartridgeaccording to the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 4. FIG. 4 is a perspective view of a preferredembodiment printhead cartridge 40 a according to the present invention.The printhead cartridge 40 a comprises an inkwell 42, and a tapeautomated bonding (TAB) structure 44 mounted on the inkwell 42. Theinkwell 42 has a front surface 45 and a bottom surface 49. The TAB 44 ismounted on the front surface 45, and wraps around to the bottom surface49. The TAB 44 includes a plurality of contacts 46 a, each in electricalconnection with a printhead 48 by way of a trace 47. All of the contacts46 a are on the front surface 45 of the inkwell 42, whereas theprinthead 48 is disposed on the bottom surface 49. The contacts 46 a arearranged in a plurality of columns 46 c. The inkwell 42 provides ink(not shown) to the printhead 48. The printhead 48 jets the ink accordingto signals received from the contacts 46 a.

Please refer to FIG. 5 with reference to FIG. 4. FIG. 5 is a perspectiveview of a printer 50 according to the present invention. The printheadcartridge 40 a is adapted for use within the printer 50. The printer 50includes a carriage 52 that holds the printhead cartridge 40 a, andcarries the printhead cartridge 40 a back and forth along a direction Xof a print track 54. With each pass along the print track 54, theprinthead cartridge 40 a jets ink onto a document 51 to perform aprinting operation. The printhead cartridge 40 a is mounted in anupright manner within the carriage 52, the bottom surface 49 facingdownwards, so that gravity may help to feed ink to the printhead 48. Theprinthead cartridge 40 a has a centerline along a direction Y—Y, whichevenly defines a first side 45R and a second side 45L of the frontsurface 45. This centerline Y—Y, a vertical bisector, is perpendicularto the direction X of the print track 54. The first side 45R has abouthalf of the total surface area of the front surface 45, with the secondside 45L having the remainder. A majority of the contacts 46 a aredisposed on the first side 45R, so that the distribution of contacts 46a on the first side 45R exceeds that of the second side 45L. That is,the number of contact columns 46 c on the first side 45R is differentfrom the number of contact columns 46 c on the second side 45L. Thedistribution of contacts 46 a is thus asymmetric with respect to thecenterline Y—Y. This asymmetric distribution is in excess of any simpledisparities brought about by parity (i.e., an odd number of contacts 46a). The first side 45R should have at least 5 percent more contacts 46 athan the second side 45L. The bottom surface 49 also has a centerlineB—B, which substantially evenly divides the bottom surface 49. Note thatthe centerline B—B aligns with the centerline Y—Y, so that if one wereto evenly split the printhead cartridge 40 a in half, one would have tocut along both the centerline Y—Y and the centerline B—B. The printhead48 lies evenly disposed along the centerline B—B.

The printhead cartridge 40 a is preferably designed to work inconjunction with a complementary printhead cartridge 40 b. For example,the printhead cartridge 40 a may hold only colored ink, whereas theprinthead cartridge 40 b will hold black ink. Please refer to FIG. 6with reference to FIGS. 4 and 5. FIG. 6 is a perspective view of theprinthead cartridges 40 a and 40 b according to the present invention,which are to be used in the printer 50. The printhead cartridge 40 balso has an asymmetrical distribution of contacts 46 b in accordancewith the present invention, with a higher distribution of contacts 46 bbeing towards the printhead cartridge 40 a. The printhead cartridge 40 bmay be thought of as a reflection along a line R—R of the printheadcartridge 40 a, as regards the distribution of the contacts 46 b withrespect to that of the contacts 46 a. Of course, the printhead cartridge40 b may have a fewer or greater number of contacts 46 b than contacts46 a. The key point is, however, that a greater number of contacts 46 aand 46 b are moved closer towards the imaginary line R—R between theprinthead cartridges 40 a and 40 b. By placing a greater percentage ofthe contacts 46 a and 46 b closer together, a size reduction can be madeon a corresponding flexible circuit board (FCB) within the carriage 52.

Please refer to FIG. 7 with reference to FIGS. 4, 5 and 6. FIG. 7 is aschematic diagram of a flexible circuit board (FCB) 70 disposed withinthe carriage 52 of the printer 50. The FCB 70 is used as a contactsurface to establish electrical connections with each contact 46 a and46 b of the printhead cartridges 40 a and 40 b, respectively. The FCB 70has a plurality of dimples 76 a, each of which establishes an electricalconnection with one corresponding contact 46 a, and a plurality ofdimples 76 b, each of which establishes an electrical connection withone corresponding contact 46 b. In this manner, by way of the FCB 70,the printer 50 is capable of sending signals to the printhead cartridges40 a and 40 b. The complementary asymmetric distributions of thecontacts 46 a and 46 b on their respective printhead cartridges 40 a and40 b leads to a greater concentration of corresponding dimples 76 a and76 b towards a center 75 c of the FCB 70, the center 75 c being boundedby the centerlines of the paired printhead cartridges 40 a and 40 b.This, in turn, leads to a corresponding decrease in the number ofdimples 76 a and 76 b on the sides 75L and 75R of the FCB 70, which lieoutside the bounds of the center 75 c. A consequence of this is thattraces 77 from the dimples 76 a and 76 b are more concentrated in thecenter 75 c of the FCB 70, and fewer traces 77 need be made that runalong the sides 75L and 75R of the FCB 70. The traces 77 may also bemade to run between two columns of dimples, such as between columns 79 aand 79 b. The sides 75R and 75L may thus be pulled in towards the center75 c, which leads to a size reduction of the FCB 70. As an extremeexample of this, if all of the contacts 46 a of the printhead cartridge40 a were placed upon the side 45R, the traces 77 a, 77 b, 77 c and 77 dwould clearly move closer towards the center 75 c of the FCB 70. Theregion thus currently occupied by the traces 77 a-77 d could thus betrimmed away from the FCB 70, leading to a further reduction in size ofthe FCB 70.

Several methods may be utilized to create an asymmetric distribution ofcontacts on a printhead cartridge so as to enjoy the correspondingresult in a size reduction of the contact surface (i.e., the FCB 70)within the printer. The preferred embodiment is depicted in FIG. 4, inwhich the centerline B—B of the TAB 44 aligns with the centerline Y—Y ofthe front surface 45. In this case, more contacts 46 a are concentratedon one side of the centerline Y—Y than on the other, leading to theasymmetric distribution of contacts 46 a. Alternatively, however, theTAB 44 itself may be moved to be asymmetric with respect to thecenterline Y—Y. Please refer to FIG. 8. FIG. 8 is a second embodiment 80of a printhead cartridge according to the present invention. Theprinthead cartridge 80 includes an inkwell 82 and a TAB 84. The inkwell82 has a front surface 85 and a bottom surface 89. The front surface 85is evenly defined by a centerline C—C into a first side 85R and a secondside 85L. The bottom surface 89 is similarly evenly divided by acenterline E—E, which aligns with the centerline C—C. The TAB 84 isdisposed on both the front surface 85 and bottom surface 89 of theinkwell 82, having a plurality of contacts 86 disposed on the frontsurface 85, and a printhead 88 on the bottom surface 89. The portion ofthe TAB 84 mounted on the front surface 85 is evenly divided by acenterline D—D, whereas the portion of the TAB 84 mounted on the bottomsurface 89 is evenly divided by a centerline F—F. The centerline D—Daligns with the centerline F—F to evenly divide the entire TAB 84. Thecontacts 86 are symmetrically disposed around the TAB 84 centerline D—Dso that, excepting parity considerations, an equal number of contacts 86are on one side of the centerline D—D as on the other side of thecenterline D—D. However, the centerline D—D of the TAB 84 is offset fromthe centerline C—C of the front surface 85. This causes more contacts 86to be disposed within the side 85R, which leads to an asymmetricdistribution of the contacts 86 on the front surface 85 with respect tothe centerline C—C. On the bottom surface 89, the printhead 88 ismounted in alignment with the centerline E—E of the bottom surface 89,rather than the centerline F—F of the TAB 84. In this manner, theprinthead 88 remains centrally aligned on the bottom surface 89, whichis preferred as only one type of inkwell 82 must thus be fashioned.

A printhead centrally aligned on the bottom surface of the inkwell isnot a prerequisite, however, of the present invention. Please refer toFIG. 9. FIG. 9 is a third embodiment 90 of a present invention printheadcartridge. In this embodiment, as in the previous embodiment 80,centerlines H—H and J—J of the TAB 94 are offset from the correspondingcenterlines G—G and I—I of the inkwell 92. However, the printhead 98 isaligned with the TAB 94 centerline J—J of the bottom surface 99.Consequently, both the contacts 96 and the printhead 98 are symmetricwith respect to the TAB 94, but are asymmetric with respect to theinkwell 92. This design is considered somewhat inferior, though, as itrequires two different types of inkwell 92: one that supports a greaterdistribution of contacts 96 on the side 95R, and another that supports agreater distribution of contacts 96 on the side 95L.

In contrast to the prior art, the present invention provides a printerthat utilizes an asymmetric distribution of contacts on the frontsurface of an ink jet cartridge inkwell. By pairing two such printheadcartridges together, each with opposing symmetries of contacts, agreater number of contacts may be brought closer together in the pairingof the printhead cartridges. For a contact surface within the printerthat is used to establish communications with the paired printheadcartridges (i.e., an FCB), a higher density of corresponding dimples arebrought towards the center of this connecting surface. The outer edgesof the surface may thus be trimmed away, leading to a size reduction ofthe surface, and consequently, reduced costs associated with theprinter.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device may be made while retainingthe teachings of the invention. For example, it may be possible to trimat least one corner of the TAB, or make the TAB into a wavy shape.Accordingly, the above disclosure should be construed as limited only bythe metes and bounds of the appended claims.

What is claimed is:
 1. An ink jet recording apparatus (IJRA) comprising:a carriage for carrying a pair of printhead cartridges, at least one ofwhich printhead cartridges has an asymmetric distribution of contacts,each printhead cartridge having a front surface with a respectivecenterline that divides the front surface into two sides havingapproximately equal areas; and a flexible circuit board (FCB) disposedwithin the carriage and used to establish electrical coupling with thepaired printhead cartridges, the FCB comprising: a contact surfacehaving a central region bounded by the centerlines of the pairedprinthead cartridges, and a peripheral region that is outside of thecentral region; a plurality of conductive traces disposed on the contactsurface; and a plurality of dimples disposed on the contact surface andelectrically coupled with the conductive traces to couple with thepaired printhead cartridges, wherein due to the asymmetric distributionof contacts on the at least one printhead cartridge, the number ofdimples in the central region exceeds the number of dimples in theperipheral region.
 2. The ink jet recording apparatus of claim 1 whereinthe number of dimples in the central region of the contact surface is atleast 5 percent greater than the number of dimples in a peripheralregion of the contact surface.
 3. The ink jet recording apparatus ofclaim 1 wherein the dimples disposed on the contact surface are arrangedin a plurality of columns.
 4. The ink jet recording apparatus of claim 3wherein the number of columns in the central region of the contactsurface is greater than the number of columns in a peripheral region ofthe contact surface.
 5. The ink jet recording apparatus of claim 4wherein the conductive traces run between the columns of dimples.
 6. Theink jet recording apparatus of claim 3 wherein the conductive traces runbetween the columns of dimples.
 7. The ink jet recording apparatus ofclaim 1 wherein the paired printhead cartridges have opposing contactsymmetries so that a greater number of contacts may be brought closertogether.
 8. The inkjet recording apparatus of claim 1 wherein thecentral region of the contact surface is bisected by an imaginary linebetween the paired printhead cartridges.
 9. A flexible circuit board(FCB) disposed within a carriage of an ink jet recording apparatus(IJRA), the FCB used to establish electrical coupling with pairedprinthead cartridges, at least one of which printhead cartridges has anasymmetric distribution of contacts, each printhead cartridge having afront surface with a respective centerline that divides the frontsurface into two sides having approximately equal areas, the FCBcomprising: a contact surface having a central region bounded by thecenterlines of the paired printhead cartridges, and a peripheral regionthat is outside of the central region; a plurality of conductive tracesdisposed on the contact surface; and a plurality of dimples disposed onthe contact surface and electrically coupled with the conductive tracesto couple with the paired printhead cartridges, wherein due to theasymmetric distribution of contacts on the at least one printheadcartridge, the number of dimples in the central region exceeds thenumber of dimples in the peripheral region.
 10. The flexible circuitboard of claim 9 wherein the number of dimples in the central region ofthe contact surface is at least 5 percent greater than the number ofdimples in a peripheral region of the contact surface.
 11. The flexiblecircuit board of claim 9 wherein the dimples disposed on the contactsurface are arranged in a plurality of columns.
 12. The flexible circuitboard of claim 11 wherein the number of columns in the central region ofthe contact surface is greater than the number of columns in aperipheral region of the contact surface.
 13. The flexible circuit boardof claim 12 wherein the conductive traces run between the columns ofdimples.
 14. The flexible circuit board of claim 12 wherein the centralregion of the contact surface is bisected by an imaginary line betweenthe paired printhead cartridges.
 15. The flexible circuit board of claim11 wherein the conductive traces run between the columns of dimples.